The present invention relates to a recoverable, especially to a heat-recoverable, article and a method for protecting or shielding a junction or discontinuity in cables or conduits and in particular relates to shielding coaxial cables and other cables having a conductive outer shield from external radio frequency interference.
Heat recoverability is characterized by the ability to undergo a permanent change in dimensions with the application of heat. In general, the property of heat recoverability can be imparted to a material having a plastic or elastic memory by expanding the material at an elevated temperature to a size greater than its normal size and then cooling while maintaining the material in the expanded size.
The prior art methods of shielding cables from external radio frequency interference have been plagued by the problem of leakage. The problem is particularly acute at a junction between two or more such cables where it is important that the continuity of the outer conductive shield be maintained in both longitudinal and circumferential directions in order to provide adequate screening against stray radiation.
The use of heat-recoverable tubing in connection with the shielding and protecting of cable junctions and the like is known. Also, the use of a heat-shrinkable tubing "sandwiched" with conductive braid is known as described in U.S. Pat. No. 3,253,619, the disclosure of which is incorporated herein by reference. Although braided shields have been used to protect coaxial cables from radio frequency interference, I have perceived that the utility of these shields could be greatly enhanced if the shield could be formed to protect the cable from high frequency radiation which is capable of penetrating the interstices between the strands of a braided shield and shaped so that it is capable of deforming uniformly when the tubing with which it is sandwiched is caused to be recovered.
It is thus an object of the present invention to provide a recoverable, especially a heat-recoverable article for effectively protecting or shielding a junction or discontinuity in conduits or cables from radio frequency interference, water, gas, solvents etc.
This and other objects are accomplished by shielding or protecting a junction or discontinuity in conduit or cable with an article comprised of a member of heat-recoverable material having a corrugated sheath disposed therein.